Charleston International Airport officials took a step Thursday toward charging travelers a fee that's already assessed by almost every other major airport in the country.

Proceeds from the so-called passenger facility charge would help defray the costs of improvement projects.

The Charleston County Aviation Authority is proposing a $3 fee, which is $1.50 less than the maximum allowed by law. Airlines tack the charge on to their fares and then forward the money to the airports.

The aviation authority awarded a contract Thursday of up to $30,000 to financial consultant Fullerton & Friar Inc. to help begin the fee approval process. That estimated 10-month procedure will involve carriers and the Federal Aviation Administration.

Many carriers scrambling to recoup money lost to soaring fuel bills are beefing up luggage fees and charging for previously complimentary services such as refreshments and even seat choices within the coach cabins.

Airports director Sue Stevens said Charleston International hopes to have the $3 fee in place by July. Savannah and Columbia charge their passengers the maximum $4.50, she said.

Stevens said the airport stands to collect $3 million to $4 million from the charge within the first year, based on last year's 1.1 million boardings. The money, which would become available in 2010, must be used for capital-improvement projects.

Authority Chairman David Jennings said renovating the nearly 25-year-old main terminal would be the first priority.

"This building has lasted us over 20 years," Jennings said. "The horizon for the useful life of the building is getting closer every day."

Stevens said terminal renovations could begin in two years, but she stressed that it's too early to say for sure.

Jennings said the airport also would look at extending its parking garage.

Of the nation's top 100 airports, 95 collect a passenger facility charge, FAA spokeswoman Kathleen Bergen said. Greenville-Spartanburg International Airport is the only other South Carolina airport that does not tack on the fee, she said.

Local aviation authority officials have said Charleston International resisted tapping the revenue source in the past because it didn't need to.

"The time has come," Jennings said Thursday. "We still have significant numbers of people coming through the facility, and it's our responsibility to plan for allowing them to do so."

While it's hard to say how passenger growth will be affected by the shaky economy, AirTran Airways' announcement that it would stop service to Savannah/Hilton Head International Airport next month gave Charleston an edge in the low-cost arena. Other airports reported major drops in airline traffic after this summer's gas price surge, but Jennings said Charleston saw a minimal drop.